发表机构
Cardiff University; Universität Zürich; Max-Planck-Institut für Astrophysik; Liverpool John Moores University（卡迪夫大学; 苏黎世大学; 马克斯·普朗克天体物理学研究所; 利物浦约翰摩尔斯大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
该研究通过Auriga套件的5套模拟，发现恒星质量与形态相近的银河系质量星系，其CGM因星系风金属负载不同而存在显著差异，为约束星系形成的反馈物理提供了新途径。
AI 中文摘要
星系晕介质（CGM）既是为恒星形成和星系生长提供燃料的气体库，也是恒星演化和反馈所抛射的质量、能量与金属的储存库。我们利用Auriga套件中5套银河系质量晕的宇宙学磁流体动力学模拟开展了受控实验，改变恒星反馈驱动的星系风的金属含量和能量负载。我们组合选择这些参数，使得所有5次运行在z=0时获得非常相似（在≈10%以内）的恒星质量和形态，因此在整个生命周期中产生的金属量相近。我们的模拟在这些金属最终分布的位置上存在显著差异，包括晕内的空间位置以及不同重子成分（恒星、气体盘、CGM和星系际介质）之间的分布。金属含量会影响晕气体的冷却效率，调控CGM冷气体比例和向星系的吸积率。在我们的两个极端模型之间，盘平面上方垂直高度|z|≳30 kpc处的气体金属量存在一个数量级的差异。当前通过|z|≲15 kpc处中速和高速云的吸收线测量得到的银河系晕气体金属量约束，与我们的模拟大致一致，但采用方法的差异限制了直接对比。我们的发现表明，恒星含量和形态几乎相同的星系，其CGM可能存在显著差异，这为约束星系形成模型中的反馈物理提供了一条有前景的途径。
英文摘要
The circumgalactic medium (CGM) is both the reservoir of gas that fuels star formation and galaxy growth, and the repository for the mass, energy, and metals expelled through stellar evolution and feedback. We present a controlled experiment using a suite of five cosmological magnetohydrodynamical simulations of a Milky Way-mass halo from the Auriga suite, where we vary the metal content and energy loading of galactic winds driven by stellar feedback. We chose these parameters in combination such that all five runs obtain very similar (within $\approx$10\%) $z=0$ stellar masses and morphologies and thus produce similar amounts of metals throughout their lifetimes. Our simulations differ substantially in where these metals end up, spatially within the halo and across the different baryonic components (stars, gas disc, CGM, and the intergalactic medium). The metal content affects the cooling efficiency of the halo gas, regulating the CGM cool gas fraction and the accretion rates onto the galaxy. Between our two extreme models, we report an order of magnitude difference in the median gas metallicity at vertical heights $|z| \gtrsim 30$ kpc above the disc plane. Current constraints on the metallicity of the Milky Way halo gas from absorption-line measurements of intermediate- and high-velocity clouds at $|z| \lesssim 15$ kpc are broadly consistent with our simulations, though a direct comparison is limited by differences in the adopted methods. Our findings show that galaxies with nearly identical stellar content and morphology can differ substantially in their CGM, which offers a promising avenue for constraining feedback physics within galaxy formation models.
Comments17 pages, 12 figures; submitted to MNRAS; comments are welcome
